Typical development devices include a developer bearer inside which a magnetic field generator is provided to carry developer on the surface of the developer bearer and a developer regulator to adjust the amount of developer carried on the developer bearer. Developer is carried on the surface of the developer bearer due to the magnetic force exerted by the magnetic field generator and conveyed to a development range as the developer bearer rotates. The developer regulator extends in a width direction perpendicular to the direction of rotation of the developer bearer and is disposed with a tip thereof facing the surface of the developer bearer across a predetermined clearance (i.e., a regulation gap). The developer regulator regulates the amount of developer passing through the regulation gap, carried on the developer bearer.
Typically, the magnetic field generator does not present in end portions in the width direction (i.e., axial end portions) of the developer bearer outside an image area because the end portions do not need to carry the developer. Although the axial end portions of the developer bearer are not designed to carry developer, in practice, among the developer conveyed toward the regulation gap, the developer blocked by the developer regulator is pushed to the axial end portion.
The developer that has reached the axial ends then inevitably moves through the gap between the developer regulator and the developer bearer. In the axial end portions, the effects of the magnetic force exerted by the magnet roller are small. Accordingly, it is possible that the developer leaves the surface of the developer bearer and scatters. The scattering developer can adhere to other components, resulting in contamination inside the apparatus or adhere to sheets of recording media, thus degrading image quality.